Vincenzo Nibali (Astana) regained the race lead after finishing in the lead group, six seconds ahead of Horner on the stage. Nibali leads Horner overall by three seconds, with Nicolas Roche (Saxo-Tinkoff) in third at eight seconds.

The day’s main escape consisted of Nicolas Edet (Cofidis), Alex Rasmussen (Garmin-Sharp), Dennis Vanendert (Lotto-Belisol), Jussi Viekkanen (FDJ) and Danilo Wyss (BMC Racing). The five riders built up a lead of around seven minutes at its peak.

Omega Pharma-QuickStep did more than its fair share to reel in the break’s time advantage on the day’s lumpy route. By the time the lead quintet hit the wall of the category three climb of Mirador de Ézaro – two kilometres at an average of 13 per cent, and hitting around 30 per cent in places – they had just over three minutes on the bunch.

Edet, Wyss and Vanendert quickly dropped Rasmussen and Viekkanen on the climb as they ground out their gears. The peloton also started to fall to pieces, with some riders over-geared and forced to get off and walk.

Meanwhile, Edet crested the climb solo as Wyss and Vanendert also fell back. The Frenchman managed to hang out front until 15km to go, when the largely reassembled, RadioShack-led peloton swallowed him up.

The bunch stayed together until the final two-kilometre climb to the line, when Juan Antonio Flecha (Vacansoleil) launched an attack – and just as with his similar effort on the previous day’s stage, he was caught, this time by Moreno.

Moreno carried his momentum forward despite a concerted chase by Cancellara, and eased over the line with several bike lengths to spare.

The peloton split on the ascent to the line, with Horner finding himself on the wrong side of the action and losing six valuable seconds to Nibali, thereby reliquishing the red leader’s jersey.

More hills tomorrow: the 174.3km fifth stage from Sober to Lago de Sanabria features two category three climbs.